Valves for pressurized containers (e.g., aerosol containers) are well known. One well known valve includes a mounting cup, a stem, and a seal (e.g., a grommet) disposed between and interconnecting the stem and the mounting cup. The mounting cup has a generally cylindrical sidewall, a generally flat bottom wall, and an upper curled lip at an upper end of the sidewall. A central portion extends upward from a central region of the bottom wall and defines a mounting opening through which the seal and the stem extend. The mounting cup is received in an opening on top of the container, and the mounting cup is crimped (clinched) or otherwise attached to the container. The seal is made of a resilient material and has an elongate neck which extends through the mounting opening. A seal bead extends radially outward from the neck and overlies and presses against an upper peripheral edge of the central portion to secure the seal to the mounting cup. The stem includes an elongate tubular stem body with an outlet and inlet(s) (orifices) at the upper and lower ends, respectively, and a disc (or button) at the lower end of the stem body. The stem body snugly fits through a bore defined by the seal to form a seal therebetween. The disc seats against a seat portion of the seal to form a leak proof seal when the valve is in a non-actuated position. The disc is movable away from the seat portion in an actuated position to allow product in the container, via pressure inside the container, to flow between the disc and the seat portion and through inlet(s) of the stem. Depending on the actuator used to operate the valve, the valve may function as a “vertically actuated” valve, whereby an axial force is applied to the stem to unseat the disc from the seat portion of the seal, or alternatively, as a “tilt” valve, whereby a rotational force is applied to the side of the stem to unseat the disc.
In some situations, such as when the valve is attached to an aerosol container containing a flowable product and the container is attached to a device for applying the flowable product, the device may damage the external seal bead during attachment of the device to the container including the valve. This may cause leakage, and ultimately, failure of the valve. For example, dispensing guns are used to facilitate dispensing of products, such as moisture curable one component polyurethane foam (OCF), from a container including a vertically actuated valve as described above. Typically, a gun collar (gun ring) is snap-fitted, or otherwise attached, to the valve which had been previously attached to a container, and then threaded onto, or otherwise attached to, the gun basket of a dispensing gun. As the container, with the attached valve and collar, is threaded onto the gun basket, a hub of the gun basket receives an upper end portion of the stem and seal, and a shoulder of the hub engages a shoulder of the stem to drive axial movement of the stem and unseat the stem disc from the seat portion of the seal. With conventional valves in this example, there exist conditions under which the external seal bead is pinched between the gun basket and the upper peripheral edge of the central portion of the mounting cup as a result of 1) the design of the gun basket and/or 2) the distance the gun collar allows the container to be threaded onto the gun basket. This may lead to two problems: 1) the upper peripheral edge of the central portion may damage the external bead, and even cut the external bead from the seal, in which case, there would be nothing preventing the stem and seal from being pushed into the container, causing leakage; and 2) free axial movement of the stem inside the seal has ceased, and the stem and the seal move as one, causing the seal to move axially away from the mounting cup, causing leakage between the mounting cup and the seal.